Manganese deficiency – the forgotten element

Manganese is a mineral element that is essential for strong and healthy plants and has so many roles in the metabolism that scientists are still working to understand the diverse effects of manganese in plants. Do not confuse it with magnesium, because although their names are similar, they are two totally different elements!


Functions of manganese

Manganese (Mn) plays an important role in a number of physiologic processes as a constituent of multiple enzymes and an activator of other enzymes.

Manganese superoxide dismutase (MnSOD) is the main antioxidant enzyme in the mitochondria. The mitochondria are the cell organelles in which the energy is produced, they are the energy factory of all animals and plants. Unfortunately, they are especially vulnerable to oxidative stress due to its intense activity. The superoxide radical is one of the reactive oxygen species produced in the mitochondria during the obtention of energy and it is a harmful particle for the cells. MnSOD converts the superoxide radicals into peroxide, which can be reduced to water by other antioxidant enzymes. In short, MnSOD helps convert the toxic particles that are produced in cells into water.

Another essential role of manganese in plants is that it helps in the conversion of water to oxygen during photosynthesis. In the chloroplast’s organelles of all plant cells there is a water-splitting complex formed by manganese metalloenzymes. This complex is responsible for the final photooxidation of water during photosynthesis, giving place to the oxygen that is released from the plants to the environment.

How do you recognize a manganese deficiency in plants?

Manganese (Mn) deficiency can be easy to spot in plants because, much like magnesium (Mg) deficiency, the leaves start to turn yellow and undergo interveinal chlorosis. The difference between these two is that the younger leaves near the top of the plant show symptoms first because manganese is not mobile while in magnesium deficiency show symptoms in older leaves near the bottom of the plant.

Causes of a manganese deficiency

A manganese deficiency is more common in poorly drained soils, also where organic matter levels are high, this may be especially important if you use worm manure to fertilize. On the other hand, manganese may not be available for plants if the pH of the substrate is too high.

What can you do about a manganese deficiency?

Manganese deficiency is easy to cure and growers have several options to treat these symptoms.

  • The first thing is to adjust the pH of the soil. Two materials commonly used to lower the pH of the soil are aluminum sulfate and sulfur. Aluminum sulfate will change the pH of the soil rapidly because aluminum produces acidity as soon as it dissolves in the soil. However, sulfur requires some time for conversion to sulfuric acid with the help of soil bacteria. You can read more about the pH, how to measure it and how to change it in this article.

  • If soil pH is not a problem and there is no manganese in the soil, it is important to know how to feed your plants correctly. You should use high quality plant nutrients to assure a balanced diet for your crop. If the deficiency is already advanced, you can use stimulators that contain manganese in its composition and apply them as a foliar spray. Also, some products, like Silic Boost, increase the absorption of the elements manganese and iron by the roots.